ABSTRACT This study aimed to analyse the effects of invasion by the exotic Ligustrum lucidum on mycorrhizal associations in forests of Celtis tala, and to determine the role that these fungi play in the invasion process. We analyzed colonization and response to mycorrhization of both plant species under greenhouse conditions after inoculation with soil obtained from patches of non-invaded native forests and invaded forests. The spores present in pots at the end of the experiment were counted and identified. Colonization of L. lucidum was greater in plants inoculated with invaded forest soil, whereas colonization of C. tala was greater in plants inoculated with non-invaded native forest soil. Principal component analysis of fungal species abundance showed differences in AMF composition according to host plant and forest type. The results show that L. lucidum establishes symbiosis with native AMF, which triggers changes in community structure. These changes favored the mycorrhization of L. lucidum and interfered with the mycorrhization of C. tala. AMF may have either a direct or indirect role in the invasion process, not only benefiting the invasive species but also preventing the regeneration of native plants.

ABSTRACT Knowledge of the occurrence and diversity of arbuscular mycorrhizal fungi (AMF) in National Parks is essential for the establishment of policies for conservation. The aim of this study was to characterize the AMF communities in the Patagonian Altoandina region in Nahuel Huapi National Park, Argentina. We surveyed AMF spores associated with the rhizospheres of 9 plant species in the Patagonian Steppe (PS), Challhuaco Hill (ChH), Catedral Hill (CH), and Tronador Hill (TH) regions and detected a total of 27 Glomeromycota species. Acaulospora laevis was dominant at all sites. The AMF community was dominated by Acaulosporaceae, as regards the number of species and contribution of each one to the total number of spores. Three Glomeromycota families were detected at PS, the site with the lowest elevation; whereas five to six families were detected at ChH, CH, and TH. Cluster analysis indicated that the AMF communities were grouped according to habitat. We concluded that certain patterns of the AMFcommunity structure detected were equivalent to those of high-altitude environments from other studies, while others were unique to the Patagonian region; thus suggesting that historical influences like dispersion and speciation played a critical role in shaping AMF community composition in such high-altitude environments.